Production fluid control device and method for oil and/or gas wells

ABSTRACT

A device and method for selectively controlling the flow of production fluid through a tubing string in an oil and gas well according to which a housing is connected to a tubing string for insertion into the well, and well fluid is passed from the ground surface into the housing. The housing is provided with a plug to establish well fluid pressure in the housing to actuate a packer and/or other ancillary devices. The plug can be removed from the hosing by increasing the pressure of the well fluid in the housing above a predetermined value, thus permitting the flow of production fluid from the formation zone, through the housing and the tubing string, and to the ground surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on provisional application Ser. No. 60/060,691filed Sep. 23, 1997.

BACKGROUND OF THE INVENTION

The present invention relates to a fluid control device for use in anoil and/or gas well and, more particularly, to such a device forselectively controlling the flow of production fluid from a producingformation adjacent the well, through the well, and to the groundsurface.

In a typical oil and gas production well, a casing is provided to linethe well and is provided with perforations adjacent the formation toreceive the production fluid. A tubing string is run into the casing andhas an outer diameter less than that of the inner wall of the casing toform an annulus. A packer is placed in the annulus to direct theproduction fluid into the lower end of the tubing string for passageupwardly through the tubing string for recovery above ground.

It is often advantageous, and sometimes necessary, to utilizehydraulically-actuated packers and other ancillary devices, especiallywhen operating in deviated or horizontal well sections. To this end, theflow of production fluid into and through the tubing string is blocked,and well fluid is introduced into the tubing string from the groundsurface, to create a relatively high fluid pressure which is used toactuate these devices. After this operation is completed the tubingstring must be opened to permit the flow pf production fluid through thestring and to the ground surface. Therefore, pump-out plugs, or thelike, are often provided in the tubing string which normally block fluidflow through the string and which are ejected from the string when theflow of production fluid is desired. However, these plugs are relativelylarge and, when ejected, must either be removed from the wellbore bycoiled tubing or the like, which is very expensive, or left in thewellbore, which may cause problems during the life of the well.

Also, disc subs have been used which incorporate a disc that normallyblocks fluid flow through the tubing string and which breaks in responseto fluid pressure acting thereon when flow is desired. However, thesedisc subs suffer from the fact that the pressure that has to be appliedto break the disc is often excessive and unpredictable. Therefore, othertechniques have been devised to break the discs to permit fluid flow.For example, steel bars have been used which are dropped into the wellor run on wireline or coiled tubing. This has disadvantages since thebroken disc forms debris in the wellbore and, if the well has a deviatedor horizontal section, a drop bar or wireline run is very unreliable.

Still other techniques for selectively blocking the flow of productionfluid through the tubing string involve wireline set/retrieved tubingplugs. However, these devices require a “profile” sub that has to beadded to the tubing string and require the use of wireline intervention,as well as increased risk and expense.

Therefore, what is needed is a relatively inexpensive and reliabledevice for selectively controlling the flow of production fluid througha tubing string in an oil and/or gas well which minimizes the amount ofdebris left in the wellbore yet which can be activated with apredictable and relatively low amount of fluid pressure. Also what isneeded is a device of the above type which does not require a profilesub or any actuation device to be dropped into the tubing string or runinto the string on wireline or coiled tubing.

SUMMARY OF THE INVENTION

The present invention, accordingly, is directed to a device forselectively controlling the flow of production fluid through a tubingstring in an oil and gas well according to which one end of a housing isconnected to a tubing string for insertion into the well, and well fluidis passed from the ground surface the one end of the housing. The otherend of the housing is closed to establish well fluid pressure in thehousing to actuate a packer and/or other ancillary devices. The otherend of the housing can be opened by increasing the pressure of the wellfluid in the housing above a predetermined value, thus permitting theflow of production fluid from the formation, through the housing and thetubing string, and to the ground surface.

Several advantages result from the device and method of the presentinvention. For example, they are relatively inexpensive and reliable,yet minimize the amount of debris left in the wellbore. Also, the devicecan be activated with a predictable and relatively low amount of fluidpressure, and does not require a profile sub or any actuation devicethat must be dropped into the tubing string or run into the string onwireline or coiled tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial elevation-partial sectional view depicting aninstallation in an oil and/or gas well including the device of thepresent invention.

FIGS. 2 and 3 are vertical sectional views of the device of the presentinvention depicting two operational modes of the device.

FIGS. 4 and 5 are views identical to those of FIGS. 2 and 3,respectively, but depicting an alternate embodiment of the device of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The well fluid control device of the present invention is designed to beused downhole in an oil and/or gas wall depicted in FIG. 1. Thereference numeral 10 refers, in general to a well casing that lines thewell bore and receives a tubing string 12 having an outer diameter thatis less than the casing to define an annulus 14 between the tubingstring and the casing. The tubing string 12 can be lowered into thecasing 10 from the ground surface in any conventional manner such as byusing a wireline, coiled tubing, or the like. A packer 16 is disposed inthe annulus 14 and extends around a lower portion of the tubing string12, as viewed in FIG. 1. The packer 16 is preferably hydraulicallyactuated and since it is conventional, it will not be described indetail. A plurality of perforations 10a are formed through the casing 10below the end of the tubing string 12. The perforations 10a permitproduction fluid from a formation zone F to flow into the casing 10 andthrough the tubing string to the ground surface, in a manner to bedescribed.

The control device of the present invention is referred to, in general,by the reference numeral 20, and is attached to the lower end portion ofthe tubing string 12. The control device 20 is adapted to selectivelycontrol the flow of the production fluid through the tubing string 12and to the ground surface, and to permit well fluid from the groundsurface to be introduced into the tubing string 12 and pressurizedsufficiently to actuate the packer, and any ancillary devices.

To this end, and with reference to FIG. 2, the control device 20comprises a sub 22 which is internally threaded at its upper end portion22a, as viewed in FIG. 2, to mate with a corresponding externallythreaded lower end portion of the tubing string 12 (FIG. 1). The controldevice 20 also includes a tubular housing 24 having an internallythreaded upper end portion 24a that threadedly engages a correspondingexternally threaded lower end portion 22b of the sub 22. A plurality ofset screws 26, one of which is shown in FIG. 2, are angularly spacedaround the circumference of the upper end portion 24a of the housing 24and extend through aligned opening in the latter end portion and thelower end portion 22b of the sub 22, to secure the sub to the housing. Aseal ring 28 extends between an outer surface portion of the sub 22 anda corresponding inner surface portion of the housing 24.

A lower sub 30 is also provided which has an internally threaded upperend 30a portion that threadedly engages a corresponding externallythreaded lower end portion 24b of the housing 34. A plurality of setscrews 32, one of which is shown in FIG. 2, are angularly spaced aroundthe circumference of the upper end portion 30a of the lower sub 30 andextend through aligned opening in the latter end portion and the lowerend portion 24b of the housing 24, to secure the connection between thesub and the housing. A seal ring 34 extends between and outer surfaceportion of the housing 24 and a corresponding inner surface portion ofthe sub 30. The lower end portion of the lower sub 30 is externallythreaded so as to enable internally threaded subs of ancillary equipment(not shown) to be attached to the device 20 as needed.

A tubular piston 40 is slidably mounted in the housing 24 and its outersurface is stepped to define an upper end portion 40a, an intermediateportion 40b extending just below the upper end portion, and a portion40c that extends from the intermediate portion 40b to the lower end ofthe piston. The outer diameter of the intermediate portion 40b isgreater than the diameter of the portions 40a and 40c, and a pair ofaxially spaced seal rings 42a and 42b extend between the outer surfaceportion of the intermediate portion 40b and corresponding inner surfaceportions of the housing 24. The lower end of the piston 40 tapers to arelative sharp point for reasons to be described.

A ring 46 is disposed in a space defined between the outer surface ofthe upper end portion 40a of the piston 40 and the corresponding innersurface of the housing 24. The ring 46 receives a plurality ofangularly-spaced shear pins 48 that extend through aligned openings inthe ring 44 and the upper end portion of the piston 40. The shear pins48 thus normally retain the piston 40 in its upper position shown inFIG. 2, but are adapted to shear in response to a predetermined shearforce applied thereto to release the piston and permit slidable movementof the piston downwardly in the housing 24, as will be explained. Aplurality of angularly-spaced openings 40d, one of which is shown in thedrawings, extend through the upper end portion 40a of the piston 40 justbelow the openings that receive the shear pins 48, for reasons that willalso be explained.

The inner surface of the housing 24 is stepped so that the innerdiameter of its lower portion is less than that of its upper portion todefine an annular chamber 50 between the inner surface of the upperportion of the housing 24 and a corresponding outer surface of thepiston 40. The relatively large-diameter intermediate portion 40b of thepiston 40 defines the upper boundary of the chamber 50, and thereduced-diameter portion of the housing 24 defines its lower boundary.The chamber 50 accommodates movement of the intermediate portion 40b ofthe piston 40 during its downward movement. A seal ring 52 extendsbetween an outer surface portion of the piston portion 40c and acorresponding inner surface portion of the reduced-diameter portion ofthe housing 24. Thus, the chamber 50 extends between the seal rings 42band 52 to isolate the chamber from fluids and to maintain the pressurein the chamber at atmospheric pressure for reasons to be described.

The lower sub 30 has a stepped inner surface that defines a shoulderthat receives a frangible disc 56, and a seal being 58 extends betweenthe shoulder and the disc. The disc 56 is made of frangible material,such as glass that is adapted to shatter when impacted by the pointedlower end of the piston 40 with sufficient force. The end of the housing24 abuts the disc 56, and a seal ring 60 is disposed between the latterend and the disc. A seal ring 62 extends between the outer surface ofthe disc 56 and the corresponding inner surface of the sub 30. The disc56 is capable of withstanding relatively large differential pressuresacting on its respective upper and lower surfaces far in excess of theamount of force required to shears the pins 48 as will be described.

In operation, a well fluid is introduced into the casing 10 from theground surface at a sufficient pressure to block the flow of productionfluid from the formation zone F (FIG. 1) through the perforations 10aand into the casing 10. When it is desired to recover the productionfluid, the tubing string 12 is run into the casing 10 with the device 20attached to the lower end of the string, and with the packer 16 providedin a section of the string just above the device 20.

The presence of the disc 56 in the lower end portion of the device 20permits well fluid from the ground surface to be introduced into thetubing string 12 at an increased pressure to establish a hydrostaticload to allow the packer 16, and/or any ancillary devices to behydraulically set in a conventional manner. During this operation, thepressure of the well fluid in the device 20 acts on the upper end of thepiston 40 in a downwardly direction and on the lower end of the pistonin an upwardly direction. Since the area of the annular upper endsurface of the piston 40 is greater that the area of its annular lowerend surface, a differential force is established which applies a shearforce to the pins 48. However, the pins 48 are designed to normallyresist the force and thus maintain the piston in its upper, staticposition of FIG. 2. This increased fluid pressure in the device 20 iscontrolled so that the resultant differential pressure across the disc56 caused by the latter pressure acting on the upper surface of the disc56, and the well fluid in the annulus 14 acting on the lower surface ofthe disc, does not exceed the design limit of the disc.

When the packer 16, and any ancillary devices, have been set inaccordance with the above and it is then desired to recover productionfluid from the formation zone F, the pressure of the well fluid in thetubing string 12 is increased. Since the upper end surface of the piston40 has a larger area than its lower end, the shear force applied to thepins 48 will be increased until the pins are sheared, with the openings40d increasing the volume of well fluid available to act on the uppersurface of the piston 40. The piston 40 is thus forced downwardly andits pointed lower end strikes the disc 56 with enough force to shatterit. It is noted that the relatively low atmospheric pressure existing inthe chamber 50 does not impede this downward movement of the piston 40and that the above increase in hydrostatic load is selected so that thedisc 56 can withstand the resulting differential pressure acting on itsupper and lower surfaces. The pressure of the well fluid in the tubingstring 12 is then reduced as necessary to allow the well fluid in theannulus, and then the production fluid from the formation zone F, toflow through the device 20 and the tubing string 12 to the groundsurface and be recovered.

The device 20 thus enjoys several advantages. For example, it isrelatively inexpensive and reliable, yet can withstand a great deal ofdifferential fluid pressure and be activated with a predictable andrelatively low amount of fluid pressure. Also, the amount of debris leftin the wellbore is minimized since the material used in the frangibledisc 56 is such that, one broken by the piston 40, it is reduced tosmall slivers or particles that can be flowed or circulated from thewell. Further, the device 20 does not restrict the inner diameter of thewell bore and thus allows other tools to pass through it and it does notrequire a profile sub or any actuation device that must be dropped intothe tubing string or run into the string on wireline or coiled tubing.

The embodiment of FIGS. 4 and 5 is similar to the embodiment of FIGS. 2and 3 and identical components are given the same reference numerals.According to the embodiment of FIGS. 4 and 5, a device 20′ is providedwhich is identical to the device 20 of the embodiment of FIGS. 2 and 3with the exception that, in the former device, a plurality ofangularly-spaced ports, one of which is shown by the reference numeral24c in FIGS. 4 and 5, are provided through the wall of the housing 24.The ports 24c are axially located relative to the housing 24 so thatthey register with the lower portion of the chamber 50 when the piston40 is retained in its upper, static position by the shear pins 48 asshown in FIG. 4. Thus, the above-mentioned well fluid that is initiallyin the annulus 14 to maintain the production fluid in the formation zoneF, as discussed above, will enter the chamber 50 through the ports 24cand exert an upwardly-directed pressure against the lower annularsurface of the relative large diameter portion 40b of the piston 40.

As in the previous embodiment, the upper surface of the piston 40 has agreater surface area than the lower surface due to the relatively largediameter portion 40b. Therefore, there is one downwardly-directed forcecaused by the well fluid in the interior of the housing 24 acting on theupper surface of the piston 40 as described above and an upwardlydirected force caused by the well fluid in the interior of the housingacting on the lower surface of the piston, also as described above. Inaddition, there is an additional upwardly-directed force by the wellfluid in the annulus 14 acting on the lower annular surface of therelatively large diameter portion 40b of the piston. Also as in theprevious embodiment, the shear pins 48 are designed to shear at apredetermined shear force applied thereto based on the difference of theabove-mentioned forces acting on the piston 40. However, in thisembodiment, the shear force can be much less than that of the embodimentof FIGS. 2 and 3 due to the presence of the last-mentioned upwardlydirected force. Otherwise the operation of the device 20′ is identicalto that of the device 20 of the embodiment of FIGS. 2 and 3.

The device 20′ of the embodiment of FIGS. 2 and 5 thus enjoys all of theadvantages of the device 20 of the embodiment of FIGS. 2 and 3 and, inaddition, the amount of shear force required to shear the pins 48, andtherefore actuate the piston 40 of the former device is mush less thanthat of the latter device.

It is understood that variations can be made in the foregoing withoutdeparting from the scope of the invention. For example, although thetubing string 12 and the devices 20 and 20′ are shown extendingvertically, it is understood that this is only for the purpose ofexample and that, in actual use, they can extend at an angle to thevertical. Therefore, the use of the terms “upper”, “lower”, “upwardly”,“downwardly”, and the like, are only for the purpose of illustrationonly and do not limit the specific orientation and position of any ofthe components discussed above.

It is understood that other modifications, changes and substitutions areintended in the foregoing disclosure and in some instances some featuresof the invention will be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the scope of theinvention.

1. A method for controlling the flow of production fluid from aformation zone in an oil and/or gas well to the ground surface, themethod comprising the steps of introducing a fluid into the well fornormally preventing the flow of production fluid from the formationzone, inserting a tubing string including a packet and a housing intothe well, passing well fluid from the ground surface into one end of thehousing, closing the other end of the housing for creating a well fluidpressure in the housing to set the packer in the annulus between thetubing string and the wall of the well, increasing the pressure of thewell fluid in the housing sufficient to open the other end of thehousing and thus permit the flow of production fluid from the formationzone through the housing and the tubing string and to the groundsurface.
 2. The method of claim 1 comprising the steps of retaining apiston in the housing, the increased-pressure well fluid in the housingreleasing the piston and sliding the piston in the housing against theplug for opening the housing.
 3. The method of claim 2 wherein a plugcloses the other end of the housing and the piston fractures the plug.4. The method of claim 2 wherein the well fluid in the housing acts onthe respective ends of the piston with a force corresponding to therespective areas of the surfaces of the latter ends, wherein the area ofthe surface of one of the ends of the piston is greater than the area ofthe surface of the other end of the piston to create a differentialforce, and wherein the piston slides in response to the differentialforce exceeding a predetermined value.
 5. The method of claim 4 whereinthe housing and the piston extend substantially vertically, with thesurface of the upper end of the piston having a greater area that thesurface of the lower end of the piston so that the piston slidessubstantially downwardly in the housing.
 6. A device for controlling theflow of production fluid from a formation zone in an oil and/or gas wellto the ground surface, the device comprising: a housing adapted to beconnected at one end to a tubing string for insertion into the well andforming an annulus between the outer surface of the housing and theinner surface of the well, the one end of the housing being open forreceiving well fluid from the ground surface; a plug disposed in theother end of the housing for permitting the increase in pressure of thewell fluid in the housing; a piston disposed in the housing; a pluralityof shear pins connected to the piston for normally retaining the pistonin the housing, the shear pins responding to the pressure of the wellfluid in the housing exceeding a predetermined value for shearing topermit slidable movement of the piston in the housing against the plugto remove the plug from the housing and open the other end of thehousing to permit the flow of production fluid from the formation zone,through the housing and the tubing string and to the ground surface; apacker extending in the annulus, that portion of the annulus extendingbetween the packer and the formation zone containing well fluid underpressure to normally maintain the production fluid in the formationzone; and a port defined in the wall of the housing to permit the latterwell fluid to enter the housing and act against the piston.
 7. A methodfor controlling the flow of production fluid from a formation zone in anoil and/or gas well to the ground surface, the method comprising thesteps of: connecting one end of a housing to a tubing string forinsertion in a vertical orientation into the well; passing well fluidfrom the ground surface into the one end of the housing; normallyclosing the other end of the housing for creating a well fluid pressurein the housing; retaining a piston in the housing so that the well fluidin the housing acts on the respective ends of the piston, the area ofthe surface of the upper end of the piston being greater than the areaof the surface of the lower end of the piston so that the fluid acts onthe respective ends of the piston to create a differential force; thepiston sliding downwardly in the housing in response to the differentialforce exceeding a predetermined value to open the other end of thehousing and thus permit the flow of production fluid from the formationzone through the housing and the tubing string and to the groundsurface; forming an annulus between the outer surface of the housing andthe inner surface of the well; setting a packer in the annulus;maintaining pressurized well fluid in that portion of the annulusextending between the packer and the formation zone to normally maintainthe production fluid in the formation zone; and permitting the latterwell fluid to enter the housing and act against the piston to change thedifferential force.
 8. A device for controlling the flow of productionfluid from a formation zone in an oil and/or gas well to the groundsurface, the device comprising: a housing adapted to be connected at oneend to a tubing string for insertion into the well, the one end of thehousing being open for receiving well fluid from the ground surface; afrangible plug extending in the housing and closing the other end of thehousing being closed to permit the pressure of the well fluid in thehousing to build up; and a piston normally retained in the housing andhaving a pointed end, the piston being responsive to the pressure of thewell fluid in the housing exceeding a predetermined value for sliding inthe housing towards the plug so that the pointed piston end fracturesthe frangible material of the plug to open the other end of the housingand permit the flow of production fluid from the formation zone, throughthe housing and the tubing string and to the ground surface.
 9. Thedevice of claim 8 further comprising a plurality of shear pins connectedto the piston for normally retaining the piston in the housing, theshear pins responding to the pressure of the well fluid in the housingexceeding the predetermined value for shearing to permit the slidablemovement of the piston.
 10. A method for controlling the flow ofproduction fluid from a formation zone in an oil and/or gas well to theground surface, the method comprising the steps of: connecting one endof a housing to a tubing string for insertion into the well; passingwell fluid from the ground surface into the one end of the housing;closing the other end of the housing with a frangible plug for creatinga well fluid pressure in the housing; and providing a piston having asharp end in the housing and adapted to respond to the pressure of thewell fluid in the housing exceeding a predetermined value and to slidein the housing until its sharp end fractures the plug to open the otherend of the housing to permit the flow of production fluid from theformation zone through the housing and the tubing string and to theground surface.
 11. The method of claim 10 further comprising the stepof retaining the piston in the housing by a plurality of shear pins, theshear pins responding to the pressure of the well fluid in the housingexceeding the predetermined value for shearing to permit the slidablemovement of the piston.
 12. A device for controlling the flow of fluidin a well, the device comprising: a housing having a bore therethrough;a frangible plug blocking flow through the bore; and a piercingstructure which pierces the plug in response to a pressure differentialbetween an interior of the housing and an atmospheric chamber, therebyopening the bore to flow therethrough.
 13. A device for controlling theflow of fluid through a tubular string in a wellbore, the devicecomprising: a housing interconnectable in the tubular string forinsertion into the wellbore to thereby form an annulus between an outersurface of the housing and the wellbore; a plug disposed in the housingand blocking fluid flow therethrough, thereby permitting an increase inpressure in the tubular string to set a packer interconnected in thetubular string; a gas chamber; a piston exposed to fluid pressure in thetubular string and to pressure in the gas chamber; at least one retainermember connected to the piston for retaining the piston againstdisplacement in the housing, the retainer member permitting displacementof the piston when fluid pressure in the tubular string exceeds pressurein the gas chamber by a predetermined amount, the piston therebypiercing the plug and opening the plug to fluid flow therethrough.
 14. Amethod for controlling the flow of fluid in a tubular string positionedin a wellbore, the method comprising the steps of: interconnecting ahousing in the tubular string, a plug in the housing preventing fluidflow through the housing and thereby permitting pressure in the tubularstring to be increased; retaining a piston in the housing, the pistonbeing exposed to pressure in the tubular string and pressure in a gaschamber; setting a packer interconnected in the tubular string byincreasing pressure in the tubular string; then further increasingpressure in the tubular string, thereby achieving a predetermineddifferential between pressure in the tubular string and pressure in thegas chamber; displacing the piston in response to the predeterminedpressure differential; and piercing the plug in response to the pistondisplacing, thereby permitting fluid flow through the housing.
 15. Adevice for controlling the flow of fluid in a tubular string in a well,the device comprising: a housing adapted to be interconnected in thetubular string for insertion into the well; a frangible plug disposed inthe housing and preventing fluid flow through the housing; and a pistonnormally retained against displacement in the housing, the piston beingresponsive to pressure in the housing exceeding pressure in a gaschamber by a predetermined amount to displace toward the plug and causeat least a portion of the plug to be broken, thereby permitting fluidflow through the housing.
 16. A method for controlling the flow of fluidthrough a tubular string in a wellbore, the method comprising the stepsof: interconnecting a housing in the tubular string, a frangible plug inthe housing preventing fluid flow through the housing; providing achamber in the housing, the chamber being isolated from fluidcommunication with an interior of the tubular string, and the chamberbeing isolated from fluid communication with an annulus formed betweenthe tubular string and the wellbore; providing a piston in the housing,the piston being nonresponsive to pressure in the annulus andnonresponsive to a difference in pressure between the annulus and theinterior of the tubular string; increasing pressure in the tubularstring, thereby achieving a predetermined differential between pressurein the interior of the tubular string and pressure in the chamber; anddisplacing the piston in response to the pressure increasing step,thereby breaking at least a portion of the plug and permitting fluidflow through the housing.